UE Interference Coordination via ABS Patterns
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Solution Overview
Problem
Current LTE Release-8/9 inter-cell interference coordination techniques are not effective in mitigating control channel interference, especially in Macro-Femto scenarios where UEs in idle mode experience out-of-service issues due to lack of interference coordination, leading to poor user experience and reduced radio spectrum efficiency.
Innovation Solution
Enhanced inter-cell interference coordination (eICIC) method that improves UE measurements in both RRC_IDLE and RRC_CONNECTED states, and the network access procedure, specifically using simplified radio resource restrictions and enhanced RACH procedures to provide interference status information to the base station, allowing for better scheduling and mobility management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If static ICIC schemes with fractional frequency reuse are used, then deployment complexity is low and implementation is simple, but control channel interference mitigation effectiveness is insufficient
Solution Approach 1:
The patent transitions from static ICIC schemes to dynamic eICIC schemes where the network can adaptively configure ABS patterns and adjust resource allocation based on real-time interference conditions. This allows the system to dynamically respond to varying interference scenarios while maintaining manageable complexity through standardized procedures.
Solution Approach 2:
The patent changes the operational parameters by introducing almost-blank subframes with specific patterns (ABS patterns) that can be configured with different periodicities and densities. This parameter adjustment enables flexible control over interference levels while maintaining system operability.
2Reliability
If ABS is applied in macrocell to protect picocell, then inter-cell interference is reduced, but UE measurement accuracy is affected due to restricted radio resources
Solution Approach 1:
The patent segments radio resources into interference-protected resources (during ABS) and non-protected resources (during non-ABS). This segmentation allows the system to perform different types of measurements on different resource sets, improving overall measurement accuracy while maintaining interference protection.
Solution Approach 2:
The patent introduces measurement configuration messages from the serving base station as an intermediary that guides UE measurements. This intermediary provides the UE with information about which resources to measure and how to interpret measurements, resolving the conflict between interference protection and measurement accuracy.
3Reliability
If ABS is applied in femtocell for Macro-Femto scenario, then interference to macrocell is reduced, but idle mode UEs experience out-of-service issues due to lack of interference coordination
Solution Approach 1:
The patent applies preliminary action by configuring ABS patterns in advance in femtocells before idle mode UEs attempt to access the network. This pre-configuration ensures that protected subframes are available for macrocell UEs attempting to access or reaccess the network, preventing out-of-service conditions.
Solution Approach 2:
The patent implements feedback mechanisms where base stations exchange interference coordination information and where UEs provide measurement reports that inform network decisions. This feedback loop enables the network to adapt ABS configurations to maintain idle mode UE connectivity while providing interference protection.
4Area of stationary object
If UE performs measurements on all subframes, then measurement coverage is complete, but measurement results are largely affected by interfering macrocell signals
Solution Approach 1:
The patent applies local quality by directing UEs to perform different types of measurements on different subframe types. Specifically, UEs perform mobility-related measurements on non-ABS subframes where interference is present, but interference coordination measurements on ABS subframes where interference is protected, optimizing measurement quality for each purpose.
Data Source
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AI summary
A method of inter-cell interference coordination is provided for UE measurements and network access procedure. In a first embodiment, a UE in idle mode performs measurements on received radio signals applying a simplified radio resource restriction for interference coordination. The UE determines the restricted radio resource without receiving explicit measurement configuration. In a second embodiment, during various phases of a network access procedure, the UE indicates its interference status and/or additional interference information to its serving base station to enhance interference coordination. In a third embodiment, the UE in connected mode performs measurements on both interference-protected transmission resources and non-interference-protected transmission resources. The UE measurement results are used for scheduling, radio link monitoring, and/or mobility management to increase radio spectrum efficiency and to improve user experience.